The present invention relates to a sensor arrangement and an engine management device for a combustion engine, a particularly to a sensor arrangement which detects variables indicative of engine load.
The traditional design of sensor arrangements and engine management devices for combustion engines, e.g., for motor vehicles, is such that all the sensors mounted on the engine and the throttle-valve control element are accommodated in their own housings and individually cabled to an engine control unit which contains the entire intelligence for the engine management. Thus, a typical engine control unit, for example a main processor, includes a unit for calculating engine load connected thereto, a safety processor coupled to the main processor for performing prescribed safety functions for an electrically driven throttle valve, a throttle-valve position controller and a corresponding driver stage for driving the throttle-valve control element. The unit for calculating engine load is fed the output signals from an induction-pipe pressure sensor, from an intake-air temperature sensor, and from a mass air-flow sensor. Moreover, the output signal from the throttle-valve position sensor is supplied both to the unit for calculating engine load, as well as to the throttle-valve position controller of the engine control unit. All of the sensors named are positioned separately from one another at proper locations on an air intake section. The throttle-valve control element is usually designed, for example, as a d.c. servomotor having a potentiometer which functions as a throttle-valve position sensor.
German Patent No. 34 05 935 C2, which describes a special throttle-valve control device for a motor vehicle combustion engine, discloses integrating in one shared assembly: a throttle-valve servomotor driven by a processor, a corresponding throttle-valve position sensor, a throttle-valve assembly, in which the throttle valve is arranged on a throttle-valve shaft, the electronic components of an input stage, which is able to feed a setpoint signal to a position control loop, the position control loop itself, as well as a driver stage, which is able to be supplied with an output signal from the position control loop and via which driving signals can be supplied to the servomotor. The intention here is to integrate components in this manner to reduce the outlay required for cabling.
The demand for increased integration and microtechnical implementation of electrical automotive components, such as sensors and actuators, is discussed in the periodical essay by K. Ehlers, Mikrosystemtechnikxe2x80x94Voraussetzung fxc3xcr Funktionsverdichtung und Aufwxc3xa4rtsintegration im Kraftfahrzeug, tmxe2x80x94Technisches Messen [Microsystem Technologyxe2x80x94Conditions for Condensing Functions and Upward Integration in Motor Vehicles, tmxe2x80x94Industrial Metrology] 60 (1993) 9, page 347, which essay is hereby incorporated by reference herein.
In addition to potentiometers, a number of other types have been proposed as throttle-valve position sensors, in particular those based on a contactless measuring principle, such as optical, magnetic, and capacitive sampling. Sensors of this kind are described, for example, in German Patent Application Nos. DE 38 26 408 A1, DE 42 43 778 A1 and DE 42 43 779 A1, as well as in German Patent Nos. DE 40 14 885 C2, DE 40 34 991 C2, and DE 41 18 218 C2 and in U.S. Pat. No. 4,994,739.
An object of the present invention is to make available a sensor arrangement and an engine management device of compact construction. The sensor arrangement and engine management device require only little cabling expenditure and, accordingly, are fail-safe, and render possible an engine management which is precise and, thus, optimized with respect to fuel consumption and exhaust emissions. When necessary, the sensor arrangement and engine management device permit a multi-sensor processing of measured data with the use of redundant sensor information.
The present invention therefore provides a sensor arrangement for a combustion engine, characterized in that at least two sensors (7a, 7b, 7c, 10) from a sensor set are microintegrated in a modular unit. The sensor set includes a mass air-flow sensor, an intake-air temperature sensor, an induction-pipe pressure sensor, and a throttle-valve position sensor.
The present invention also provides an engine management device for a combustion engine, comprising a sensor device (7a, 7b, 7c) for detecting variables indicative of engine load; engine load evaluator (8) for determining engine load on the basis of measured values supplied by the sensor device; and a throttle-valve position control loop having a throttle-valve position controller (8), which generates/produces a throttle-valve adjustment signal using the determined engine load, a throttle-valve servo unit 6 and a throttle-valve position sensor (10). The engine management device is characterized in that the sensor device is made up of a sensor arrangement as stated above, in which the at least two sensors (7a, 7b, 7c, 10), the engine load evaluator (8) for determining engine load and/or the throttle-valve position controller (8) are microintegrated in the modular unit (2).
In the sensor arrangement, at least two of the four sensors, namely intake-air temperature sensor, induction-pipe pressure sensor, mass air-flow sensor, and throttle-valve position sensor, are microintegrated in a shared modular unit. Preferably, all four sensors are integrated in the modular unit in this manner, using microtechnology. This microintegration of a plurality of sensors, which, in particular, are those which sense variables indicative of engine load, economizes on cabling expenditure, permits a compact construction of the sensor arrangement, and offers the condition of a multi-sensor processing of measured data, it being possible, when necessary, to utilize redundant sensor information, for example to enhance accuracy and reliability in acquiring engine load estimates.
Provision is made in the engine management device for such a sensor arrangement. In this context, the engine management device contains a modular unit, in which not only the two to four named sensors of this sensor arrangement are microintegrated, but also the evaluator for determining engine load, preferably in the form of an engine load estimation circuit, and or the throttle-valve position controller, as well. The need is eliminated in this engine management device for cabling expenditure for the components integrated in the modular unit, with microtechnology preferably being used to integrate all four named sensors of the sensor arrangement, the evaluator for determining engine load, and the throttle-valve position controller into the modular unit, which then can be described as a microintegrated, intelligent throttle-valve position- and load-detecting module. Integrating the evaluator for determining engine load and/or the throttle-valve position controller in the modular unit, and thus configuring it outside of the customary engine control unit, means that the corresponding sensor data no longer need to be communicated to the engine control unit. Moreover, the entire engine management device can be assembled relatively compactly in the modular unit, due to the microintegration of the named components.
Also provided is an engine management device with a further development, the throttle-valve position sensor participates in the microintegration, for which it is constructed in a relatively simple, special manner, however in such a way that it still provides the required measuring accuracy.
An engine management device with another further development has a brushless synchronous motor as a throttle-valve control element, the Hall-effect sensor elements usually provided for such a motor for detecting its operating position, being used simultaneously as a throttle-valve position sensor that is included in the microintegration. This allows comparatively exact throttle-valve positional measurements over the entire adjustment range.
In the case of a further developed engine management device, also integrated in the modular unit using microtechnology are power electronics, which are used for energizing the power-consuming components of the modular unit and, in some instances, of a throttle-valve servomotor.
Another further development is an engine management device in which additionally microintegrated in the modular unit is a safety processor unit, which is set up for performing the necessary safety functions for the electrical throttle-valve control. Configuring this processor unit that is usually contained in the engine control unit outside of this unit and placing it in the modular unit promotes the simplification of the engine control unit and, above all, helps one to economize on cabling expenditure and signal-transmission processes, particularly when the evaluator for determining engine load and the throttle-valve position controller are integrated in the modular unit.